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LT6119-1/LT6119-2

611912f

For more information www.linear.com/LT6119-1

applicaTions inForMaTion

number can be multiplied by the

θJA value, 160°C/W, to

find the maximum expected die temperature. Proper heat

sinking and thermal relief should be used to ensure that

the die temperature does not exceed the maximum rating.

LE Pin

The LE pin is used to enable the comparator’s output latch.

When the LE pin is high, the output latch is enabled and

the comparator outputs will stay low once tripped. When

LE is low, the comparator output latches are disabled and

the comparators operate transparently. To continuously

operate the comparators transparently, the LE pin should

be grounded. Do not leave the LE pin floating.

Power-On Reset

During start-up, the state of the comparator outputs can-

not be guaranteed. To guarantee the correct state of the

comparatorsoutputsonstart-up,apower-onreset(POR)is

required. A POR can be implemented by holding the LE pin

low until the LT6119 is in such a state that the comparator

outputs are stable. This can be achieved by using an RC

networkbetweentheLE,V+andGND,asshowninFigure7.

When power is applied to the LT6119, the RC network

causes the voltage on the LE pin to remain below the VIL

(0.5V) threshold long enough for the comparator outputs

to settle into the correct state. The LE pin should remain

below 0.5V for at least 100µs after power-up in order to

Output Current Limitations Due to Power Dissipation

The LT6119 can deliver a continuous current of 1mA to the

OUTA pin. This current flows through RIN and enters the

current sense amplifier via the SENSEHI pin. The power

dissipated in the LT6119 due to the output signal is:

POUT = (VSENSEHI – VOUTA) • IOUTA

Since VSENSEHI ≈ V+, POUTA ≈ (V+ – VOUTA) • IOUTA

There is also power dissipated due to the quiescent power

supply current:

PS = IS • V+

The comparator output current flows into the comparator

output pin and out of the V– pin. The power dissipated in

the LT6119 due to each comparator is often insignificant

and can be calculated as follows:

POUTC1,C2 = (VOUTC1,C2 – V–) • IOUTC1,C2

The total power dissipated is the sum of these

dissipations:

PTOTAL = POUTA + POUTC1 + POUTC2 + PS

At maximum supply and maximum output currents, the

total power dissipation can exceed 100mW. This will

cause significant heating of the LT6119 die. In order to

prevent damage to the LT6119, the maximum expected

dissipation in each application should be calculated. This

Figure 7. RC Network Achieves Power-On Reset

LT6119

110k

60V

V+

VLE

0.1µF

611912 F07

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